APP (Aperture Pixelpost Plugin) uploads the selected picture from your Aperture library to you pixelpost blog without having to export the picture first, and then uploading it manually.
You just have to fill in all the required fields, and press the upload button. No need for any pixelpost plugins.
Drag the downloaded file to ~/Library/Application Support/Aperture/Plug-ins/Export/. Also make sure you have an image export preset with the same resolution as your images on your website.
You can get it right HERE